1. Field of the Invention
The present invention relates to a new and improved method for arranging a mechanically activated refraction system for a twin lanyard used in fall arrest. Additionally, this invention relates to a method for creating a retractable lifeline with twin retractable reels for the take-up of webbing or cable. Additionally this invention relates to a method for creating a lightweight retractable reel located in the center of a lanyard that can be used to take-up webbing from both ends of the webbing at the same time. Additionally, this invention relates to a method for activating an internal locking bar on a retractable take-up reel by the use of an over-center spring that can be re-positioned under light load to create a normally open or normally locked condition of operation.
2. Known Art
Fall arrest lanyards are used in most industrial and commercial applications requiring fall arrest for individual workers to attach those workers to fall arrest anchors. These lanyards may be in the form of fixed length steel or webbing shock-absorbing lanyards or variable length shock-absorbing retractable lanyards. The fixed length lanyards are usually lighter in weight but limit mobility due to their fixed length. They also introduce the possibility of free-falls equal to twice their length if the fall arrest anchor is at or below the foot level of the worker. The great advantage of the retractable lanyard is that (if the retractable is located overhead) the free-fall distance is just the lock-up distance of the retractable (usually less than 12-in.). The disadvantage of the retractable lanyard is that it is usually heavier than a fixed length webbing lanyard.
A problem with using shock-absorbing lanyards for fall-arrest is encountered when a worker must move from one work site to another that is farther away than the length of his retractable or fixed length lanyard. When this occurs, the worker is usually forced to disconnect from his anchorage and move or free-climb without fall-arrest protection until he reaches his next workstation and can reconnect. To solve this problem, manufacturers have created what is called a “twin lanyard”. This consists of a shock-absorbing element to which 2 fixed length lanyards are connected. When using a twin lanyard, a worker can be mobile and move from one workstation to another without ever being disconnected from an anchor point. Movement with this type of twin lanyard is accomplished as follows:                1. Connect Lanyard A to Anchor I,        2. Move to Anchor 2 and connect Lanyard B        3. Return to Anchor I and disconnect Lanyard A        4. Move to Anchor 3 and connect Lanyard A        5. Return to Anchor 2 and disconnect Lanyard B        6. Move to Anchor 4 and connect Lanyard B (and so on)        
The worker has now moved from workstation I to workstation 4 without ever being disconnected.
Another problem encountered when using fixed length twin lanyards is entanglement with the webbing when the lanyard is not attached to an overhead anchorage. Typically the free-end of the lanyard leg that is not attached overhead is connected back to the harness. This leaves a loop in the lanyard at about knee-height. When a worker bends over or stoops down this lanyard leg can slip behind the workers heel and cause him to tumble forward off balance as he begins to stand erect. For this reason some manufacturers have developed small retractable lanyards that attach to the worker's harness and act similar to a fixed length shock-absorbing lanyard except that they keep the lanyard length within the retractable so that it does not become entangled with the worker. The following preferred embodiment of the present invention relates to a method for creating a twin retractable lanyard, and also a method for creating twin retractables that can be positioned in the center of a fixed length retractable lanyard webbing to cause that webbing to shorten in length so that it will decrease fall distance and avoid entanglement.
A preferred embodiment of the present invention also relates to a method for reducing the forces encountered in the locking pawl mechanism of retractable lanyards. In all current designs a locking pawl is energized either centripetally or centrifugally to engage (or lock into) a locking sperrad on the webbing drum to stop the drum rotation and arrest the fall. The abrupt forces that are encountered with this type of engagement can often lead to damage to the pawls and locking mechanism. This present invention provides a new method to separate the locking pawls from the engagement mechanism and uses them only to activate a mechanism that moves the positioning location of an over-center spring so that a locking bar can be pivoted into place to stop the rotation of the drum, thus relieving the forces on the locking pawls. This re-positioning of the over-center spring also means that rebound cannot unlock the drum causing ratcheting of the load because the over-center spring holds the locking bar in its locked position until being reset. Examples of mechanisms that can be used to activate the locking bar can be found throughout the automotive seat-belt retraction mechanism art, and an examples of this art can be found in U.S. Pat. No. 6,254,191 to Yamamoto, et al.; U.S. Pat. No. 5,622,327 to Heath , et al.; U.S. Pat. No. 6,283,398 to Specht, which are incorporated herein in their entirety by reference, together with the references cited therein.